Material work-feeding mechanism and control means therefor



March 26, 1963 c. R. BACKLIN MATERIAL WORK-FEEDING MECHANISM AND CONTROL MEANS THEREFOR Filed March 9, 1961 3 Sheets-Sheet 1 IN VEN TOR. C Z 0 6/766 1?. Backli/z ATTOIP/VEYJ' Mn Mm h N ww emu mm (Q NNVQQN I N March 26, 1963 'c. R. BACKLIN 3,

MATERIAL WORK-FEEDING MECHANISM AND CONTROL MEANS THEREFOR Filed March 9, 1961 3 Sheets-Sheet 2 66 /m 2 70 I so 2 l 7 III, \7 I I 2 i I Z! I -L J-- L i 61 V I 6.9 JZ 55/ 1/ INVENT0R. Clara/we P. VBac/Uuz March 26, 1963 c. R. BACKLIN MATERIAL WORK-FEEDING MECHANISM AND CONTROL MEANS THEREFOR 5 Sheets-Sheet 3 Filed March 9, 1961 INVENTOR. Cid/"6 nae E1 Back I 01/ E II State aten I warm Patented; Mar. 26, 1963 fifire This invention relates to a work-feeding mechanism for sewing machines having a feed dog operable in timed relation to the operation of the sewing machine to impart movement to a workpiece therein. More specifically, it pertains to a simple control means for reversing and/or altering the feed of material by the work-feeding mechamsm.

It has been the practice in some commercial sewing operations to finish off a seam by a reverse stitching operation and it is an object of this invention to provide simple and effective means for achieving this result.

It is an important object of the invention to provide a simple control of the work-feeding mechanism for sewing machines in which a reversal in direction of feed is effected without interrupting the operation of the sewing machine.

It is also an object of the invention to provide an easily operated and accurate control of the work-feeding mechanism in which reversal of direction of feed is effected by merely varying the relationship between the feed advance means and feed lift means without interrupting the timed relation between the work-feeding mechanism and the sewing machine.

According to the invention, the above objects are achieved by separately connecting the feed advance means and feed lift means to the main 'drive shaft of the sewing machine to be driven thereby in a predetermined manner whereby, cooperatively, they impart movement in an elliptical path to the feed dog. In order to reverse the direction of material feed of the feed dog, means are provided for predeterminately altering the drive connection to the feed advance means relative to the feed lift means so that the direction of travel of the feed dog along its elliptical path is reversed.

' In one form of the invention, the feed advance means includes a rock shaft connected through link means to a rocker arm adapted to be rocked by the main drive shaft about a point substantially midway between its ends. The link means, which is movably connected to the rocker arm, is adapted, when connected adjacent one end of the arm, to communicate rocking movement in one direction to the rock shaft and, when connected adjacent the other end of the arm, to communicate rocking movement to the shaft in the reverse direction. Intermediate positions of the link means relative to the rocker arm function to operatively vary the length of the arm, thereby varying the length of rocking movement imparted to the rock shaft and consequently varying the feed or stitch length movement of the feed dog.

It is, therefore, also an object of the invention to provide a work-feeding mechanism in which the stitch length is readily varied, in either the forward or reverse direction of operation of the feed dog, by merely varying the length of movement imparted to the feed advance means.

It is further an object of the invention to provide a work-feeding mechanism which is readily reversible and in which there are means for adjustably predetermining the feed stitch length in either the forward or reverse direction of operation of the mechanism.

The simple control means of the present invention for the feed means comprises a pivoted manually actuated arm connected to the link means for shifting the drive connection between the rock shaft and rocker arm, which manually actuated arm is preferably normally urged to a position to effect a forward feed and when moved from the normal position alters the length and/or direction of the stitching depending upon the extent of movement. To facilitate the control, the arm has an adjustable pin cooperating with the upper and lower edges of an elongate V-shaped opening in a plate secured to the machine. The V-shaped opening is so arranged that the pin is normally urged to contact the upper edge to provide a predetermined forward feed, the length of the stitch being determined by its position from the apex of the V. Operation of the pivoted arm against the urging means moving the pin to engage the lower edge of the V opening automatically reverses the feed with a stitch of the same length. As soon as the arm is released it will return to normal forward feed direction. If desired to provide a shorter stitch during the reverse or the forward feed an adjustable stop can be provided to engage the arm when moved out of normal position to provide the different length as required.

Other objects and advantages will be apparent from the specification and claims when considered in connection with the attached sheets of drawings, illustrating one form of the invention, wherein like characters represent like parts and in which:

FIGURE 1 is a plan view, partially broken away and in section, of a sewing machine embodying the workfeeding mechanism of the invention;

FIG. 2 is a fragmentary end elevational view showing, in solid and broken lines, the operating means for reversing the direct-ion of travel of the work-feeding mecharnsm;

FIG. 3 is a fragmentary elevational view, in section, taken in the direction of the arrows 3-3 in FIG. 1;

FIG. 4 is a fragmentary elevational view, in section, taken in the direction of the arrows 4-4 in FIG. 1;

FIG. 5 is a fragmentary elevational view, in section, taken in the direction of the arrows 55 in FIG. 1;

FIG. 6 is a fragmentary elevational view, in section, taken in the direction of the arrows 66 in FIG. 1;

FIG. 7 is a fragmentary elevational View taken in the direction of the arrows 77 in FIG. 1;

FIG. 8 is a fragmentary elevational view of another form of the operating means shown in FIG. 2; and

FIG. 9 is an end elevational view-showing the feed dog and feed lift means.

Referring now to the drawings for a more detailed description of the invention, a sewing machine 10 is shown of conventional design having a frame 11 provided with the usual bed plate 12 and having a post 13 extending upwardly therefrom for carrying an over arm (not shown). A main drive shaft 14 is positioned in bearings 15 and 16, in the frame, beneath and substantially parallel to the bed plate 12 and has connected at one end thereof means 17 for connecting the shaft to a motor or similar source of power. Drive means 18 are provided on the shaft for driving the needle assembly (not shown) and the usual bobbin and looper mechanism 19 carried by the frame is connected to the shaft to be driven thereby.

The sewing machine 10, according to the invention, is provided with a reversible and adjustable Work-feeding mechanism 20, of the four motion type, which includes a feed dog 21, a feed advance means 22 and a feed lift means 23. The feed advance means, which is adapted to move the feed dog 21 back and forth through a substantially horizontal plane, cooperates with the feed lift means, which is adapted to raise and lower the feed dog, through a feed dog carrier arm 24 to impart movement to the feed dog along a substantially elliptical path, whereby material is fed in the conventional manner. The feed advance means 22 and the feed lift means 23 are each independently connected to the main drive shaft of the sewing machine so that motion is imparted to the feed dog 21 in timed relation to the operation of the sewing machine. While, in accordance with the invention, the feed lift means 23 may take any form known to the art, in the illustrated form of the invention (see FIGS. 1 and 9) it includes a feed lift member 23a eccentrically connected to and driven by the main drive shaft 14 and connected to feed dog carrier arm 24 for communicating eccentric movement in the form of an up and down motion thereto. The up and down movement of the arm in timed relation to the operation of the sewing machine is imparted to the feed dog so that the dog engages the material for feeding the same in a predetermined manner.

The feed advance means 22 includes a rock shaft 25 rotatably carried in a bracket'25a of frame 11 and connected through a lever 26 to the arm 24, the arm being pivotally connected to the lever at 26:: to facilitate the up and down movement of the arm in response to the action of the feed lift means. The rock shaft, which is eccentrically connected to the main drive shaft of the sewing machine to be rocked thereby in predetermined timed relation to the operation of the feed lift means 23, normally imparts a back and forth movement to the arm 24- for advancing the material being fed by the work feeding mechanism in a forward direction as the feed lift means is in its uppermost position.

According to the invention, the rock shaft 25 is rocked by a rocker arm 27, the rocking movement of which is communicated to the rock shaft through a fork shaped link member 28 in a manner to be hereinafter explained. The rocker arm, which may take any convenient form so long as it is pivoted about a point spaced from the opposite ends of the arm, in the illustrated form of the invention is substantially arcuate and is provided with an integral parallel wing or pivot portion 29 for connecting the arm to a crank 30 which is carried in bearings 30a and 30]) positioned in brackets 30c and 30d respectively in frame 11 and is eccentrically driven by the main drive shaft. In the preferred form of the invention, as illustrated, the wing 29 is spaced from the arm and positioned midway between its ends so that the arm rocks or pivots about a point substantially equally spaced from the ends of the arm. While the crank 30 may be eccentrically driven from the main drive shaft in any known manner, in the illustrated form of the invention, the drive shaft adjustably eccentrically carries a cam 31 which operates to eccentrically drive a cam housing 32 pivotally connected at 33 to a lever 34 connected to the crank 30. It will be seen in FIG. 4 that as the main drive shaft 14 rotates, the cam 31 shifts the housing 32 from side to side thereby rocking the crank 30 and in turn the rocker arm 27. The amount of movement imparted to the rocker arm can be adjusted by adjusting the eccentricity of the cam 31 through the set screws 35.

Referring again to the link 28, which communicates rocking movement from rocker arm 27 to rock shaft 25, it will be seen that the link has one end pivotally connected at 36 to a lever 37 carried by the rock shaft. The other end of the link, which is in the form of a fork or yoke having a pair of parallel legs 33 and 39 provided with a pin 40 rotatably extending therebetween and carried in bearings 41, is movably connected to the rocker arm 27 through driving engagement of the pin 40 with a sliding block 42 positioned in an arcuate groove 43 extending lengthwise of the rocker arm. An arcuate slot 44 in the bottom of the groove 43 and extending through the rocker arm, facilitates movement of the pin 40, as will be hereinafter explained.

It will be seen that during the normal operation of the work-feeding mechanism, with the link member 28 connected adjacent one end of the rocker arm (see FIG. 7), rocking motion imparted to the rocker arm by the main drive shaft will be communicated to the rock shaft 25 through the link member 28. It will be readily understood that with the link member 28 connected to the rocker arm at the furthest point from the point of pivot of the rocker arm the longest operable arm length is achieved for imparting maximum movement to the rock shaft. It will also be understood that as the link member 28 is moved, relative to the rocker arm, toward the pivot point thereof, for shortening the operable length of the arm, the length of movement imparted to the rock shaft will be decreased and, in a work-feeding mechanism of the type herein described, a shorter stitch length will result.

An important feature of the present invention resides in the means for effecting a reversal of direction of feed of the work-feeding mechanism without stopping the operation of the sewing machine or altering the operative timing of the work-feeding mechanism relative to the sewing machine. Reversal of feed is effected by merely shifting the link member 23, relative to the rocker arm 27, through the center or pivot position thereof, so that the link member engages the arm at the opposite end. Such movement of the link member will cause a reversal in direction of the rocking movement communicated to the rock shaft in relation to the continuously operating feed lift means so that the feed dog will be moving in a reverse direction when the feed lift means is in its uppermost position, thereby engaging the material being fed for feeding it in the reverse direction. In a manner similar to that described with respect to the forward feed of the workfeeding mechanism, the reverse feed stitch length is adjustable by adjusting the position of the link member 28 relative to the rocker arm, for varying operable length of the arm in the reverse direction.

In order to vary the position of the link member 28 relative to the rocker arm 27, for effecting a reversal in the direction of feed of the work-feeding mechanism and/or adjusting the stitch length, a link 45 is provided having one end pivotally connected between the legs 38 and 39 of the link member 28 by a pin 46. The other end of the link 45 is rotatably connected through a pin 47 to an arm 48, which has it opposite end connected to a shaft 49 carried in bearings 50 positioned in brackets 51 and 52 of frame 11. A collar 53 fixedly carried by the shaft 49 abuts the bracket 51 to prevent outward longitudinal movement of the shaft. A link 54 has one end connected to the shaft 49 adjacent the side of bracket 51 directed away from collar 53 and its opposite end connected to a pin 55. The pin 55 projects outwardly of the opposite sides of the link 54 and extends parallel to the shaft 49. An elongate link 56 ha one end rotatably connected to a reduced end portion 57 of the pin 55 by a screw 58 or the like and extends upwardly through the bed plate 12 into the post 13 of the sewing machine. The other end of the link 56 is rotatably connected by means of a stepped fastener 59 to a lever 60 fixedly carried by an operating shaft 61. The operating shaft 61, which is rotatably carried in bearings 62 disposed in bosses 63 and 64 in the post 13 and which is provided with an integral shoulder 65 for preventing outward longitudinal movement of the shaft, extends outwardly of the post and has connected to the outwardly extending end thereof an operating member 66 in the form of a touch lever or the like.

According to the invention, the link 54 and elongate link 56 are normally biased upwardly so that the shaft 49, through the arm 48 and link 45, shifts and holds the link member 28 in such a position that the latter engages the rocker arm 27 adjacent an end thereof, whereby maximum rocking movement is imparted to the rock shaft for moving the material being fed in a forward direction. While this may be accomplished by any means known to the art, in the illustrated form of the invention a spring 67, of spring steel or the like, secured to the bracket 39d of the frame 11 engages the end of pin 55 directed away from elongate link 56 for biasing the pin upwardly and consequently maintaining link 54 and elongate link 56 in their uppermost positions. It will be seen that by means of the control structure heretofore described, manipulation of operating member 66 will cause the link member 28 to shift against the force of spring 67 relative to rocker arm 27, for shortening the operable length of the arm in the forward feed direction and thereafter passing through the pivot point of the arm to reverse the direction of feed and subsequently increasing the operable length of the arm in the reverse feed direction.

Referring now, specifically, to FIGS. 1 and '2 of the drawings, means are provided whereby the feed stitch length can be controlled for both the forward and reverse directions of operation of the work-feeding mechanism to provide any desired stitch length within the predetermined limits of the mechanism. A control plate 68 having a V-shaped slot 69 therein is mounted on the post 13 of the sewing machine adjacent and parallel the operating member 66 so that the center line of the slot extends parallel to the neutral position of the operating member, i.e. that position in which the operating member shifts the link member 28 to a position overlying the pivot point of rocker arm 27. The operating member 66 is provided with an elongate slot 70 adapted to movably receive a control knob 71 of the type which is adapted to be shifted along the elongate slot to a desired position and then locked in place. The control knob is provided with a pin 71a for engaging the edges of V-shaped slot 69, for a purpose to be hereinafter explained. As shown in the drawings, with the knob 71 positioned in elongate slot 70 so that the pin 71a is engageable with the V-shaped slot 69 at a point most distant from the center line of the V-shaped slot, the operating member 66 is enabled to be biased by the spring 67 into such a position that maximum stitch length is achieved in forward feed direction. By shifting the knob 71 to the left, as seen in FIG. 2, the operating member 66 is progressively moved toward its neutral position against the force of spring 67, so that the operable length of the rocker arm 27 is progressively shortened and a shorter desired stitch length is achieved. Manipulation of the operating member 66 between its forward feed position, as shown in solid lines in FIG. 2, and reverse feed position, as shown in dotted lines, will produce an identical stitch length in either the forward or reversed direction as the result of engagement of the pin 71:: with the opposite sides of V-shaped slot 69. Those conversant with the sewing art will readily understand that by means of the structure afore-described, an operator can quickly change the direction of feed of the work-feeding mechanism by merely depressing the operating member 66 and that by so doing the reverse feed stitch length will not be altered. Release of the operating member 66 will automatically return the workfeeding mechanism to forward feed direction under the force of Spring 67.

In certain sewing operations it is often found desirable to utilize a shorter stitch length whe backstitching or sewing in the reverse direction than is used in the normal forward sewing operations. Accordingly, as shown in FIG. 8 of the drawings, means may be provided for preventing the operating member 66 from moving into maximum reverse stitch length position, or into the stitch length position defined by the pin 71a of control knob 71. As shown, a threaded stud 72 is mounted on the bed plate 12 of the sewing machine for adjustably receiving a threaded reverse stitch control member 73 having a tip 74 adapted to engage the operating member 66 when the latter i moved into reverse feed position for limiting such movement to the desired stitch length. A lock nut 75 threaded on the adjusting member 73 maintains the member in adjusted position.

Thus, among others, the several objects and advantages of the invention as aforenoted are achieved. Obviously numerous changes in the structure may be resorted to without departing from the spirit of the invention as defined by the claims.

I claim:

1. In a sewing machine having a main drive shaft; a work-feeding mechanism comprising a feed dog, a feed advance means operably connected to said main drive shaft, a feed lift means operably connected to said main drive shaft, connections between said advance means and lift means and said feed dog for imparting elliptical movement to said feed dog in timed relation to the operation of said sewing machine, said feed advance means including a rock shaft connected to said feed dog, a rocker arm adapted to be rocked about a point substantially midway between its ends and eccentrically driven by said main drive shaft, link means for connecting said rocker arm to said rock shaft for communicating rocking movement thereto, said link means being normally connected to said rocker arm adjacent one end thereof for imparting rocking movement of predetermined length and direction to said rock shaft, resilient means for retaining said link means in normal position relative to said rocker arm, said link means being movable relative to said rocker arm against said resilient means to a point substantially mid way between the ends thereof for progressively shortening the length of rocking movement imparted to said rock shaft to nil and thereafter from said midpoint to a point adjacent the opposite end of said rocker arm for reversing and progressively lengthening the rocking movement imparted to said rock shaft, and means for shifting said link means relative to said rocker arm.

2. In a sewing machine having a main drive shaft; a work-feeding mechanism comprising a feed dog, a feed advance means operably connected to said main drive shaft, a feed lift means operably connected to said main drive shaft, connections between said advance means and lift means and said feed dog for imparting elliptical movement to said feed dog in timed relation to the operation of said sewing machine, said feed advance means including a rock shaft connected to said feed dog, a rocker arm adapted to be rocked about a point substantially midway between its ends and eccentrically driven by said main drive shaft, link means for connecting said rocker arm to said rock shaft for communicating rocking movement thereto, said link means being normally connected to said rocker arm adjacent one end thereof for imparting rocking movement of predetermined length and direction to said rock shaft, resilient means for retaining said link means in normal position relative to said rocker arm, said link means being movable relative to said rocker arm against said resilient means to a point substantially midway between the ends thereof for progressively shortening the length of rocking movement imparted to said rock shaft to nil and thereafter from said midpoint to a point adjacent the opposite end of said rocker arm for reversing and progressively lengthening the rocking movement imparted to said rock shaft, and manually operated means connected to said link means for shifting said link means against the force of said resilient means relative to said rocker arm.

3. In a sewing machine having a main drive shaft; a Work-feeding mechanism comprising a feed dog, a feed advance means operably connected to said main drive shaft, a feed lift means operably connected to said main drive shaft, connections between said advanoe means and lift means and said feed dog for imparting elliptical movement to said feed dog in timed relation to the operation of said sewing machine, said feed advance means including a rock shaft connected to said feed dog, an arcuate rocker arm having slot means extending substantially the full length thereof and adapted to be rocked about a point midway between its ends, said rocker arm being eccentrically connected to said main drive shaft to be rocked thereby, link means connected to said rock shaft and having a follower portion movably engaged in said slot means for communicating rocking movement to said rock shaft, means for shifting said link means relative to said rocker arm to move said follower portion in said slot whereby the length of rocking movement imparted to said rock shaft can be varied and/ or a reversal of the direction of such movement can be eflFected, and resilient means acting on said shifting means for normally biasing the follower portion toward one end of said slot means.

4. In a work-feeding mechanism including a rock shaft for advancing and retracting a feed dog, a rocker arm pivoted about a point substantially midway between its ends and connected to a main drive shaft to be rocked thereby and link means having a driving connection with said rocker arm and connected to the rock shaft for communicating rocking movement to the latter; a control means for operably shifting the driving connection relative to the rocker arm whereby the direction of movement imparted to the rock shaft can be reversed and/or the length of such movement can be varied, said control References Cited in the file of this patent UNITED STATES PATENTS Oathout Sept. 9, 1913 Pagni lune 21, 1955 Stewart Sept. 6, 1955 OTHER REFERENCES German application (KL 52a 45/01), 1,099,830, printed Feb. 16, 1961. 

1. IN A SEWING MACHINE HAVING A MAIN DRIVE SHAFT; A WORK-FEEDING MECHANISM COMPRISING A FEED DOG, A FEED ADVANCE MEANS OPERABLY CONNECTED TO SAID MAIN DRIVE SHAFT, A FEED LIFT MEANS OPERABLY CONNECTED TO SAID MAIN DRIVE SHAFT, CONNECTIONS BETWEEN SAID ADVANCE MEANS AND LIFT MEANS AND SAID FEED DOG FOR IMPARTING ELLIPTICAL MOVEMENT TO SAID FEED DOG IN TIMED RELATION TO THE OPERATION OF SAID SEWING MACHINE, SAID FEED ADVANCE MEANS INCLUDING A ROCK SHAFT CONNECTED TO SAID FEED DOG, A ROCKER ARM ADAPTED TO BE ROCKED ABOUT A POINT SUBSTANTIALLY MIDWAY BETWEEN ITS ENDS AND ECCENTRICALLY DRIVEN BY SAID MAIN DRIVE SHAFT, LINK MEANS FOR CONNECTING SAID ROCKER ARM TO SAID ROCK SHAFT FOR COMMUNICATING ROCKING MOVEMENT THERETO, SAID LINK MEANS BEING NORMALLY CONNECTED TO SAID ROCKER ARM ADJACENT ONE END THEREOF FOR IMPARTING ROCKING MOVEMENT OF PREDETERMINED LENGTH AND DIRECTION TO SAID ROCK SHAFT, RESILIENT MEANS FOR RETAINING SAID LINK MEANS IN NORMAL POSITION RELATIVE TO SAID ROCKER ARM, SAID LINK MEANS BEING MOVABLE RELATIVE TO SAID ROCKER ARM AGAINST SAID RESILIENT MEANS TO A POINT SUBSTANTIALLY MIDWAY BETWEEN THE ENDS THEREOF FOR PROGRESSIVELY SHORTENING THE LENGTH OF ROCKING MOVEMENT IMPARTED TO SAID ROCK SHAFT TO NIL AND THEREAFTER FROM SAID MIDPOINT TO A POINT ADJACENT THE OPPOSITE END OF SAID ROCKER ARM FOR REVERSING AND PROGRESSIVELY LENGTHENING THE ROCKING MOVEMENT IMPARTED TO SAID ROCK SHAFT, AND MEANS FOR SHIFTING SAID LINK MEANS RELATIVE TO SAID ROCKER ARM. 